The SpaceX Cargo Dragon resupply ship is photographed departing the space station on July 8, 2021.
NASA’s live coverage of undocking and departure is underway on NASA+. Learn how to watch NASA content through a variety of platforms, including social media.
The unpiloted SpaceX Dragon spacecraft will undock at 11:05 a.m. EST from the forward port of the space station’s Harmony module and fire its thrusters to move a safe distance away from the station.
After re-entering Earth’s atmosphere, the spacecraft will make a parachute-assisted splashdown off the coast of Florida. NASA will not stream the splashdown but will post updates on the agency’s space station blog.
Filled with nearly 6,000 pounds of crew supplies, science investigations, and equipment, the spacecraft arrived to the orbiting laboratory Nov. 5 after it launched Nov. 4 on a Falcon 9 rocket from Launch Complex 39A at NASA’s Kennedy Space Center in Florida for the agency’s SpaceX 31st commercial resupply services mission.
NASA’s Webb Finds Planet-Forming Disks Lived Longer in Early Universe
7 Min Read
NASA’s Webb Finds Planet-Forming Disks Lived Longer in Early Universe
This is a James Webb Space Telescope image of NGC 346, a massive star cluster in the Small Magellanic Cloud, a dwarf galaxy that is one of the Milky Way’s nearest neighbors.
Credits: NASA, ESA, CSA, STScI, Olivia C. Jones (UK ATC), Guido De Marchi (ESTEC), Margaret Meixner (USRA)
NASA’s James Webb Space Telescope just solved a conundrum by proving a controversial finding made with the agency’s Hubble Space Telescope more than 20 years ago.
In 2003, Hubble provided evidence of a massive planet around a very old star, almost as old as the universe. Such stars possess only small amounts of heavier elements that are the building blocks of planets. This implied that some planet formation happened when our universe was very young, and those planets had time to form and grow big inside their primordial disks, even bigger than Jupiter. But how? This was puzzling.
To answer this question, researchers used Webb to study stars in a nearby galaxy that, much like the early universe, lacks large amounts of heavy elements. They found that not only do some stars there have planet-forming disks, but that those disks are longer-lived than those seen around young stars in our Milky Way galaxy.
“With Webb, we have a really strong confirmation of what we saw with Hubble, and we must rethink how we model planet formation and early evolution in the young universe,” said study leader Guido De Marchi of the European Space Research and Technology Centre in Noordwijk, Netherlands.
Image A: Protoplanetary Disks in NGC 346 (NIRCam Image)
This is a James Webb Space Telescope image of NGC 346, a massive star cluster in the Small Magellanic Cloud, a dwarf galaxy that is one of the Milky Way’s nearest neighbors. With its relative lack of elements heavier than hydrogen and helium, the NGC 346 cluster serves as a nearby proxy for studying stellar environments with similar conditions in the early, distant universe. Ten, small, yellow circles overlaid on the image indicate the positions of the ten stars surveyed in this study.
NASA, ESA, CSA, STScI, Olivia C. Jones (UK ATC), Guido De Marchi (ESTEC), Margaret Meixner (USRA)
A Different Environment in Early Times
In the early universe, stars formed from mostly hydrogen and helium, and very few heavier elements such as carbon and iron, which came later through supernova explosions.
“Current models predict that with so few heavier elements, the disks around stars have a short lifetime, so short in fact that planets cannot grow big,” said the Webb study’s co-investigator Elena Sabbi, chief scientist for Gemini Observatory at the National Science Foundation’s NOIRLab in Tucson. “But Hubble did see those planets, so what if the models were not correct and disks could live longer?”
To test this idea, scientists trained Webb on the Small Magellanic Cloud, a dwarf galaxy that is one of the Milky Way’s nearest neighbors. In particular, they examined the massive, star-forming cluster NGC 346, which also has a relative lack of heavier elements. The cluster served as a nearby proxy for studying stellar environments with similar conditions in the early, distant universe.
Hubble observations of NGC 346 from the mid 2000s revealed many stars about 20 to 30 million years old that seemed to still have planet-forming disks around them. This went against the conventional belief that such disks would dissipate after 2 or 3 million years.
“The Hubble findings were controversial, going against not only empirical evidence in our galaxy but also against the current models,” said De Marchi. “This was intriguing, but without a way to obtain spectra of those stars, we could not really establish whether we were witnessing genuine accretion and the presence of disks, or just some artificial effects.”
Now, thanks to Webb’s sensitivity and resolution, scientists have the first-ever spectra of forming, Sun-like stars and their immediate environments in a nearby galaxy.
“We see that these stars are indeed surrounded by disks and are still in the process of gobbling material, even at the relatively old age of 20 or 30 million years,” said De Marchi. “This also implies that planets have more time to form and grow around these stars than in nearby star-forming regions in our own galaxy.”
Image B: Protoplanetary Disks in NGC 346 Spectra (NIRSpec)
This graph shows, on the bottom left in yellow, a spectrum of one of the 10 target stars in this study (as well as accompanying light from the immediate background environment). Spectral fingerprints of hot atomic helium, cold molecular hydrogen, and hot atomic hydrogen are highlighted. On the top left in magenta is a spectrum slightly offset from the star that includes only light from the background environment. This second spectrum lacks a spectral line of cold molecular hydrogen. On the right is the comparison of the top and bottom lines. This comparison shows a large peak in the cold molecular hydrogen coming from the star but not its nebular environment. Also, atomic hydrogen shows a larger peak from the star. This indicates the presence of a protoplanetary disk immediately surrounding the star. The data was taken with the microshutter array on the James Webb Space Telescope’s NIRSpec (Near-Infrared Spectrometer) instrument.
Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI)
A New Way of Thinking
This finding refutes previous theoretical predictions that when there are very few heavier elements in the gas around the disk, the star would very quickly blow away the disk. So the disk’s life would be very short, even less than a million years. But if a disk doesn’t stay around the star long enough for the dust grains to stick together and pebbles to form and become the core of a planet, how can planets form?
The researchers explained that there could be two distinct mechanisms, or even a combination, for planet-forming disks to persist in environments scarce in heavier elements.
First, to be able to blow away the disk, the star applies radiation pressure. For this pressure to be effective, elements heavier than hydrogen and helium would have to reside in the gas. But the massive star cluster NGC 346 only has about ten percent of the heavier elements that are present in the chemical composition of our Sun. Perhaps it simply takes longer for a star in this cluster to disperse its disk.
The second possibility is that, for a Sun-like star to form when there are few heavier elements, it would have to start from a larger cloud of gas. A bigger gas cloud will produce a bigger disk. So there is more mass in the disk and therefore it would take longer to blow the disk away, even if the radiation pressure were working in the same way.
“With more matter around the stars, the accretion lasts for a longer time,” said Sabbi. “The disks take ten times longer to disappear. This has implications for how you form a planet, and the type of system architecture that you can have in these different environments. This is so exciting.”
The science team’s paper appears in the Dec. 16 issue of The Astrophysical Journal.
Image C: NGC 346: Hubble and Webb Observations
Image Before/After
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt manages the telescope and mission operations. Lockheed Martin Space, based in Denver also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
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NASA DAVINCI Mission’s Many ‘Firsts’ to Unlock Venus’ Hidden Secrets
5 Min Read
NASA DAVINCI Mission’s Many ‘Firsts’ to Unlock Venus’ Hidden Secrets
The surface of Venus is an inferno with temperatures hot enough to melt lead. This image is a composite of data from NASA’s Magellan spacecraft and Pioneer Venus Orbiter.
Credits: NASA/JPL-Caltech
NASA’s DAVINCI — Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging — mission embodies the spirit of innovation and exploration that its namesake, Leonardo da Vinci, was famous for.
Scheduled to launch in the early 2030s, DAVINCI will explore Venus with both a spacecraft and a descent probe. DAVINCI’s probe will be the first in the 21st century to brave Venus’ atmosphere as it descends from above the planet’s clouds down to its surface. Two other missions, NASA’s VERITAS and ESA’s (European Space Agency) Envision, will also explore Venus in the 2030s from the planet’s orbit.
The DAVINCI spacecraft will study Venus’ clouds and highlands during two flybys. It also will release a spherical probe, about 3 feet wide, that will plunge through the planet’s thick atmosphere and corrosive clouds, taking measurements and capturing high-resolution images of the Venusian surface as it descends below the clouds.
Here are some of DAVINCI’s coming “firsts” in Venus exploration:
Exploring Solar System’s One-of-a-Kind Terrain
The DAVINCI mission will be the first to closely explore Alpha Regio, a region known as a “tessera.” So far found only on Venus, where they make up about 8% of the surface, tesserae are highland regions similar in appearance to rugged mountains on Earth. Previous missions discovered these features using radar instruments, but of the many international spacecraft that dove through Venus’ atmosphere between 1966 and 1985, none studied or photographed tesserae.
Thought to be ancient continents, tesserae like Alpha Regio may be among the oldest surfaces on the planet, offering scientists access to rocks that are billions of years old.
By studying these rocks from above Alpha Regio, DAVINCI scientists may learn whether ancient Venus had continents and oceans, and how water may have influenced the surface.
Photographing One of the Oldest Surfaceson Venus
The DAVINCI probe will capture the first close-up views of Alpha Regio with its infrared and optical cameras; these will also be the first photos of the planet’s surface taken in more than 40 years.
With surface temperatures reaching 900° F and air pressure 90 times that of Earth’s, Venus’ harsh environment makes exploration challenging, while its opaque atmosphere obscures direct views. Typically, scientists rely on radar instruments from Earth or Venus-orbiting spacecraft to study its terrain.
But DAVINCI’s probe will descend through the atmosphere and below the clouds for a clear view of the mountains and plains. It will capture images comparable to an airplane’s landing view of Earth’s surface. Scientists will use the photos to compile 3D maps of Alpha Regio that will provide more detail than ever of Venus’ terrain, helping them look for rocks that are usually only made in association with water.
Unveiling Secrets of Venus’ Mysterious Lower Atmosphere
The DAVINCI mission will be the first to analyze the chemical composition of Venus’ lower atmosphere through measurements taken at regular intervals, starting from approximately 90,000 feet above the surface and continuing until just before impact.
This region is critical because it contains gases and chemical compounds that may originate from Venus’ lower clouds, surface, or even subsurface.
For example, sulfur compounds detected here could indicate whether Venusian volcanoes are currently active or were active in the recent past. Noble gases (like helium or xenon), on the other hand, remain chemically inert and maintain stable concentrations, offering invaluable clues about Venus’ ancient history, such as the planet’s past water inventory.
By comparing Venus’ noble gas composition with that of Earth and Mars, scientists can better understand why these planets — despite forming from similar starting materials — evolved into dramatically different worlds.
Moreover, DAVINCI’s measurements of isotopes and trace gases in the lower atmosphere will shed light on Venus’ water history, from ancient times to the present, and the processes that triggered the planet’s extreme greenhouse effect.
State-of-the-Art Technology to Study Venus in Detail
Thanks to modern technology, the DAVINCI probe will be able to do things 1980s-era spacecraft couldn’t.
The descent probe will be better equipped than previous probes to protect the sensitive electronics inside of it, as it will be lined on the inside with high-temperature, multi-layer insulation — layers of advanced ceramic and silica fabrics separated by aluminum sheets.
Venus’ super thick atmosphere will slow the probe’s descent, but a parachute will also be released to slow it down further. Most Earth-friendly parachute fabrics, like nylon, would dissolve in Venus’ sulfuric acid clouds, so DAVINCI will have to use a different type of material than previous Venus missions did: one that’s resistant to acids and five times stronger than steel.
By Lauren Colvin, with Lonnie Shekhtman NASA’s Goddard Space Flight Center, Greenbelt, Md.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is the principal investigator institution for DAVINCI and will perform project management for the mission, provide science instruments, as well as project systems engineering to develop the in-situ probe flight system that will enter the atmosphere of Venus. Goddard also leads the overall science for the mission with an external science team from across the United States. Lockheed Martin Space in Denver, Colorado, will build the carrier/relay spacecraft. DAVINCI is a mission within the Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.
NASA, SpaceX Adjust Dragon Undock Date Due to Weather
International Space Station Configuration. Six spaceships are parked at the space station including the SpaceX Dragon Freedom, the SpaceX Dragon cargo spacecraft, the Northrop Grumman Cygnus resupply ship, the Soyuz MS-26 crew ship, and the Progress 89 and 90 resupply ships.
Mission managers waved off the planned return of a Dragon resupply spacecraft on Sunday, Dec. 15, due to forecasted unfavorable weather conditions at the splashdown sites off the coast of Florida. NASA and SpaceX now are targeting no earlier than Monday, Dec. 16, for the next undocking opportunity of NASA’s SpaceX 31st commercial resupply services spacecraft.
Crew Studies Physics and Biology, Preps for Spacewalk, Dragon Undocking Adjusted
An orbital sunrise crowns Earth’s horizon in this photograph from the International Space Station as it orbited 261 miles above Brazil.
A space exposure experiment, a micro-algae study, and eye exams topped the research schedule for the Expedition 72 crew members at the end of the week. The orbital residents also continue to gear up for a spacewalk planned for next week at the International Space Station.
NASA astronaut and station Commander Suni Williams spent most of her day inside the Tranquility module working on the Nanoracks Bishop airlock. She was joined at the beginning of her shift by NASA Flight Engineer Butch Wilmore who helped her prepare the Euro Materials Aging (EMA) experiment for installation inside Bishop. Afterward, she inspected one portion of the EMA study that will observe organic molecules and how they adapt to the external space environment.
NASA Flight Engineer Don Pettit looked at another segment of the EMA hardware that will expose a variety of materials to outer space to monitor how they age over time. Finally, NASA Flight Engineer Nick Hague inspected the Bishop airlock with the EMA experiment inside, closed its hatch, and prepared the airlock for its upcoming depressurization.
On Monday, the Canadarm2 robotic arm will detach Bishop with the EMA inside from Tranquility and maneuver it toward the Columbus laboratory module. Next, the EMA will be robotically installed on the Bartolomeo research platform attached to the outside of Columbus. The external investigation will operate outside Columbus for about a year.
Hague at the beginning of his shift on Friday, swapped samples of micro-algae inside the BioLab incubator located in Columbus. Researchers are exploring the potential of micro-algae as a way to remove carbon dioxide, produce oxygen, and grow food on spacecraft. At the end of the day, Williams partnered with Pettit and Wilmore for eye exams using standard medical imaging hardware found in a doctor’s office on Earth. The trio were joined by ground doctors monitoring in real-time who want to understand how living in weightlessness affects vision and the human eye.
Two cosmonauts continue their preparations for a spacewalk on Thursday, Dec. 19, to remove external science experiments and relocate European robotic arm hardware. Roscosmos Flight Engineers Alexey Ovchinin and Ivan Vagner began Friday installing components on their Orlan spacesuits. Next, the duo pedaled on an exercise bicycle for a pre-spacewalk fitness assessment. Finally, the cosmonauts wrapped up the day’s suit work installing lights, batteries, and video cameras they will wear on their spacesuits during the planned six-hour and 40-minute spacewalk next week.
Roscosmos Flight Engineer Aleksandr Gorbunov trained to use the European robotic arm reviewing the laptop computers that support the robotic arm attached to the Nauka science module. Following that work, the first-time space flyer swapped out life support hardware then installed Earth observation gear to view the effects of natural and human-caused catastrophes in different wavelengths.
Mission managers waved off the planned return of a Dragon resupply spacecraft on Saturday, Dec. 14, due to forecasted unfavorable weather conditions at the splashdown sites off the coast of Florida. NASA and SpaceX now are targeting no earlier than Sunday, Dec. 15, for the next undocking opportunity of NASA’s SpaceX 31st commercial resupply services spacecraft.
